A roller mill equipped with a classifying unit that pulverizes a solid fuel such as coal and classifies a fine powder smaller than a predetermined particle size is known (refer to Patent Document 1, for example). The roller mill disclosed in Patent Document 1 includes a classification auxiliary cone in which a rotary classifying unit is disposed. The classification auxiliary cone includes a plurality of drift plates in an upper end portion thereof. These drift plates change the flow of the solid fuel to a sideways swirling flow toward the rotary classifying unit.
The roller mill disclosed in Patent Document 1 guides the solid fuel, rising due to hot air, into the interior of the classification auxiliary cone in a sideways swirling flow produced by the drift plates, and causes a coarse powder included in the solid fuel to fall downward from an inner wall surface of the classification auxiliary cone. The coarse powder that falls from the classification auxiliary cone is once again pulverized by a pulverizing roller on a table. Fine powder smaller than a predetermined particle size and classified by the rotary classifying unit inside the classification auxiliary cone is guided to an area outside the roller mill.